Acute renal failure in the intensive care unit today

Continuous Veno-Venous Hemofiltration in Critically Ill Patients with Multiple Organ Failure

18 critically ill patients, with multiple organ failure (MOF) (from shock either septic, n = 15, or cardiogenic, n = 3), oliguria and increase in BUN and creatinine were treated with pump driven, high flux continuous veno-venous hemofiltration (CVVH). Replacement fluids were administered in predilution mode. All patients were under respiratory support and vasoactive drugs, and received early nutritional support (N input: 0.2–0.3 g/kg/day). Mean duration of treatment was 9.2 days and mean ultrafiltrate production was 21.4 l/day; treatment resulted in a significant reduction of both urea nitrogen and creatinine blood levels (-20 and -40% of initial values respectively) in spite of a very severe catabolism. The total amount of urea nitrogen removed through CVVH ranged from 15 to 73 g/day (mean 33.5), the median value of urea nitrogen clearance was 12.8 ml/min with a median ultrafiltration coefficient of 0.8. The mean duration of hemofilters was 69 hours (38–108); the efficacy of filters remained stable throughout the entire lifespan and changes were made in case of sudden decrease of ultrafiltration (< ml/min). No major complication was observed in over than 4000 hours of treatment. Pump driven, high flux CVVH proved effective in the control of water electrolyte balance and metabolic homeosthasis in a group of critically ill, hemodynamically unstable, catabolic patients with MOF and acute renal failure. In no case we had to add intermittent hemodialysis or to use hemodiafiltration. The constant extracorporeal blood flow and the stable efficacy of hemofilters allowed an easy control of the overall effectiveness of this technique.

Does Nephrectomy for Trauma Increase the Risk of Renal Failure?

Renal failure is a feared complication following operations for severe trauma. Injuries to the kidney may be managed by nephrectomy or nephrorrhaphy. Nephrectomy may increase the risk of renal failure in already at-risk trauma patients. Nephrectomy for trauma should be avoided to the extent possible because it is associated with renal failure. From a prospectively collected trauma database, 59 patients with nephrectomy were matched at 1:1 ratio with 59 patients with nephrorrhaphy. Matching criteria were age (+/- 5 years), Injury Severity Score (+/- 3), abdominal Abbreviated Injury Score (+/- 1), and mechanism of injury (blunt or penetrating). The rates of renal function compromise (defined as a serum creatinine level >2 mg/dl for more than 2 days) and renal replacement therapy (continuous or intermittent) were compared in the two groups. The two groups were well-matched and similar with regard to injury severity and organs injured. Between nephrectomy and nephrorrhaphy patients, there were no differences in renal function compromise (10% vs. 14%, p = 0.57), renal replacement therapy (5% vs. 0%, p = 0.12), length of hospital stay (19 +/- 26 vs. 20 +/- 21, p = 0.8), and mortality (15% vs. 12%, p = 0.59). Salvaging the injured kidney does not seem to offer an obvious clinical benefit regarding postoperative renal function. Given the increased operative complexity of nephrorrhaphy in comparison to nephrectomy and the frequent need to abbreviate the operation in patients with severe trauma, nephrectomy should not be avoided when appropriate.

Use of creatinine clearances to monitor the effect of low-dose dopamine in critically ill surgical patients

INTRODUCTION

Despite uncertain evidence of its efficacy, "low-dose dopamine" (2-5 microg/kg/min) has often been used to augment renal perfusion in critically ill surgical patients. The 2-h creatinine clearance (CC) has been shown to be a monitor of renal function in critically ill patients. We therefore studied the use of sequential CC determinations to monitor the effect of low-dose dopamine (LDD) in surgical intensive care unit (SICU) patients. We hypothesized that sequential CC measurements could demonstrate whether individual patients had positive responses in renal function to LDD.

METHODS

Data were prospectively collected for patients on LDD in a university SICU. CC were recorded for these patients immediately before and after the institution of LDD or before and after the cessation of LDD. APACHE II scores, gender, urine creatinine, age, blood pressure, heart rate, and urine output (UO) were also recorded for these patients; P < 0.05.

RESULTS

Twenty-four pairs of CC values were observed during the study. The mean APACHE II score for the patients was 15.1. In 10 cases after initiation of LDD, the mean CC increased from 52.5 +/- 23.7 ml/min to 68.1 +/- 33.8 ml/min (P = 0.056). UO also increased from 48.0 +/- 27 to 75.9 +/- 49 ml/h (NS). In 14 cases after discontinuation of LDD, CC decreased from 85.6 +/- 36.3 ml/min to 63.6 +/- 45.5 ml/min (P = 0.044) and UO decreased from 105.1 +/- 73.9 to 89.6 +/- 76.7 ml/h (NS). Overall, 13 of the 24 patients had a 25% change or more in CC upon initiation or cessation of LDD.

CONCLUSIONS

LDD institution increased CC in individual patients in the SICU population. Because using LDD in the absence of a discernable improvement in renal function is costly and may harbor risks, we recommend following CC in patients on LDD to determine which patients derive benefit from the intervention.

Infrequent occurrence of amphotericin B lipid complex-associated nephrotoxicity in various clinical settings at a university hospital: a retrospective study

BACKGROUND

Lipid-based formulations of amphotericin B (AMB) have been shown to significantly lessen the occurrence of nephrotoxicity associated with the conventional form of AMB. A MEDLINE search of literature published from 1983 to 2002, using the search terms amphotericin B and nephrotoxicity, identified only 1 large, randomized, prospective trial that has tried to compare the nephrotoxicity rates among lipid-based AMB formulations. Using the nephrotoxicity surrogate marker of doubling of serum creatinine (SCr) level, the investigators reported a high rate of AMB lipid complex (ABLC)-associated nephrotoxicity (42.3%). However, enrollment in that study was limited to only febrile neutropenic patients.

OBJECTIVE

This retrospective study estimated the rate of ABLC-associated nephrotoxicity in various clinical settings at a university hospital and compared that rate with previously reported rates of nephrotoxicity.

METHODS

Data from adult neutropenic and nonneutropenic patients receiving ABLC were collected and the degree of nephrotoxicity was determined using 2 definitions: (1) doubling of baseline SCr level using the peak value within the first 7 days, and (2) end-of-therapy doubling of baseline SCr level using the end-of-therapy value.

RESULTS

Data from 33 patients (20 men, 13 women; mean age, 48.6 years) were collected. Using these definitions of ABLC-associated nephrotoxicity, only 2 cases (6.1%) were observed. This rate was significantly below the 42.3% rate reported in the only large published study (95% CI, 1.7-19.6; P < 0.001). The median change in SCr level was 0.1 mg/dL (range, -1.1 to 4.3 mg/dL). Rates of change were higher in patients who died during hospitalization, but the difference was not significant. Use of concomitant nephrotoxic agents did not account for significant changes in SCr level.

CONCLUSIONS

Data from this study suggest that ABLC infrequently causes clinically significant nephrotoxicity. Therefore, when formulary decisions are made in the selection of a drug for use in various clinical settings, earlier data derived from a single study in febrile neutropenic patients that suggested a significantly higher rate of nephrotoxicity should be interpreted cautiously. Larger trials with more diverse patient populations are needed to better characterize institutional rates of ABLC-associated nephrotoxicity and to aid formulary decision makers.

Continuous renal replacement therapy: our experience in intensive care unit

Continuous Renal Replacement Therapy (CRRT) indication is still discussed. We report our experience on 98 patients affected with Multiple Organ System Failure (MOSF) and renal failure (acute or chronic) requiring dialysis and timely treated by CRRT. Mortality after 5 days of ICU permanence was 60.2%; the remaining 39 patients were discharged within 21 days and received CRRT treatment for 6.36 +/- 5.59 days. APACHE II score was not able to predict the outcome of patients suffering from acute renal failure (ARF). On the contrary, Systemic Inflammatory Response Syndrome (SIRS) incidence was significantly higher in deceased patients compared to recovered patients. In conclusion, it is important to start dialytic treatment immediately when patients affected with MOSF show renal function damage, even if at an initial stage, in order to improve patients' survival. Moreover a multidisciplinary approach is preferable in ICU patients treatment for not underestimating the management of metabolic and infective complications, the nursing care, and nutritional support.

Acute renal failure and dialysis in the chronically critically ill patient

Acute renal failure is a common clinical problem in the intensive care unit (ICU) and is associated with significant morbidity and mortality. There is no "magic bullet" to prevent acute renal failure or to modify the clinical course of established renal failure. The approach to therapy is directed to the early initiation of dialysis therapy. Continuous dialysis therapy is becoming the preferred form of dialysis in the ICU.

The patient at risk for acute renal failure. Recognition, prevention, and preoperative optimization

Despite major advances in critical care medicine and extracorporeal renal support, the treatment of established postoperative ARF remains unsatisfactory and costly. The essential elements of perioperative renal preservation are early recognition of high-risk patients, preoperative optimization of fluid status and cardiovascular performance, intraoperative maintenance of renal perfusion, and avoidance of nephrotoxins. Pharmacologic interventions directed at preventing postoperative ARF are under intense investigation but presently are limited to renal transplant surgery.

Prolonged low-dose dopamine infusion induces a transient improvement in renal function in hemodynamically stable, critically ill patients: a single-blind, prospective, controlled study

OBJECTIVE

To evaluate the length of the effects of long-term (48 hrs), low-dose dopamine infusion on both renal function and systemic hemodynamic variables in stable nonoliguric critically ill patients.

DESIGN

Prospective, single-blind, controlled clinical study.

SETTING

University hospital, 19-bed multidisciplinary intensive care unit.

PATIENTS

Eight hemodynamically stable, critically ill patients with a mild nonoliguric renal impairment (creatinine clearance between 30 and 80 mL/min).

INTERVENTIONS

Each patient consecutively received 4 hrs of placebo, followed by a 3 microg/kg/min dopamine infusion during 48 hrs, then a new 4-hr placebo period. We measured cardiac output and other hemodynamic variables by using a pulmonary artery catheter. The bladder was emptied to determine urine volume and to collect urine samples. Measurements were performed at six times: after the initial control of 4 hrs of placebo (C1); after 4 hrs (H4), 8 hrs (H8), 24 hrs (H24), and 48 hrs (H48) of dopamine infusion; and after the second control of 4 hrs of placebo (C2).

MEASUREMENTS AND MAIN RESULTS

We saw no significant change in systemic hemodynamic variables with dopamine at all times of infusion. Diuresis, creatinine clearance, and the fractional excretion of sodium (FENa) at C1 and C2 were not different. Urine flow, creatinine clearance, and FENa increased significantly 4 hrs after starting dopamine (for all these changes, p < .01 vs. C1 and C2). The maximum changes were obtained at H8, with an increase of 50% for diuresis, 37% for creatinine clearance, and 85% for FENa (for all these changes, p < .01 vs. C1 and C2). But these effects waned progressively from H24, and both creatinine clearance and FENa at H48 did not differ from control values.

CONCLUSIONS

In stable critically ill patients, preventive low-dose dopamine increased creatinine clearance, diuresis, and the fractional excretion of sodium without concomitant hemodynamic change. These effects reached a maximum during 8 hrs of dopamine infusion. But despite a slight persistent increase in diuresis, improvement in creatinine clearance and FENa disappeared after 48 hrs. According to these data, it is likely that tolerance develops to dopamine-receptor agonists in critically ill patients at risk of developing acute renal failure.

Comparison of the renal effects of low to high doses of dopamine and dobutamine in critically ill patients: a single-blind randomized study

OBJECTIVE

The renal effects of dopamine in critically ill patients remain controversial. Low-dose dobutamine has been reported to improve renal function. We compared the effects of various doses of dopamine and dobutamine on renal function in critically ill patients.

DESIGN

Prospective, single-blind, randomized study.

SETTING

University hospital, 19-bed multidisciplinary intensive care unit.

PATIENTS

Twelve hemodynamically stable patients with mild nonoliguric renal impairment.

INTERVENTIONS

Each patient randomly received four different doses of dopamine and dobutamine (placebo, 3, 7, and 12 microg/kg/min). Each infusion lasted for 4 hrs. Cardiac output and systemic hemodynamic variables were measured using a pulmonary arterial catheter at the beginning (HO) and the end (H4) of each infusion. The bladder was emptied at HO and H4 to determine urine volume and to collect samples.

MEASUREMENTS AND MAIN RESULTS

The cardiac index increased significantly with both dopamine and dobutamine (p < .001). Mean arterial pressure (MAP) increased, with the maximum effect of 20% seen with 12-microg/kg/min dopamine infusion (p < .01). No change in MAP was seen with dobutamine. Dobutamine infusions did not change any renal variables. Conversely, all dopamine infusions significantly increased diuresis, creatinine clearance, and the fractional excretion of sodium (p < .01). Creatinine clearance increased from 61+/-16.9 (SD) mL/min to a maximum of 85.7+/-30 mL/min at the 7-microg/kg/min dose; fractional excretion of sodium increased from 0.26%+/-0.28% to a maximum of 0.62%+/-0.51% at the 12-microg/kg/min dose (p < .01). During dopamine infusions, there was a significant relationship between MAP and creatinine clearance (p = .018).

CONCLUSIONS

At all doses studied, 4-hr infusions of dopamine significantly increased creatinine clearance, diuresis, and the fractional excretion of sodium in stable critically ill patients. Conversely, dobutamine did not modify these variables. Although the level of MAP might partially contribute to the improvement in renal variables, it is more likely that the activation of renal dopamine receptors played a prominent role.

Prognosis in acute renal failure of septic origin: a multivariate analysis

The goal of the present study was to identify variables associated with the outcome of patients with acute renal failure (ARF) of septic origin, using multivariate analysis. The records of 168 patients were reviewed retrospectively and a crude mortality of 74% was found. Both univariate as well as multivariate analysis demonstrated an association between mortality and variables which depended on patient related factors. These included age over 60 years and several underlying diseases such as pneumonia, peritonitis, and organ dysfunction. Only one variable (late oliguria) related to the ARF itself. Thus, outcome seems related to underlying disease more than to severity of ARF.

A simple and early prognostic index for acute renal failure patients requiring renal replacement therapy

Recent advances in technology have not substantially changed the high mortality rate associated with acute renal failure (ARF). To obtain a simple, valid prognostic index, we retrospectively evaluated the relative importance of demographic data, causes (acute insults) of renal failure, and comorbid clinical conditions for the outcome in 102 ARF patients who received renal replacement therapy with an overall mortality rate of 65% (66 of 102). There were no significant differences between survivors and nonsurvivors in age and gender. Mortality according to acute insults was similar to that of the whole population studied. Of the 10 clinical conditions at the time of the first renal replacement therapy, mechanical ventilation (p = 0.0002), cardiac failure (p = 0.0006), hepatic failure (p = 0.003), central nervous system dysfunction (p = 0.005), and oliguria (p = 0.04) were found to be significantly related to mortality by univariate analysis. Furthermore, multivariate analysis demonstrated that only mechanical ventilation, cardiac failure, and hepatic failure were significant risk factors. Survival was directly related to the number of significant variables in univariate analysis: zero, 89% (8 of 9); one, 62% (21 of 34); two, 19% (5 of 27); three, 10% (2 of 20); four, 0% (0 of 8); five, 0% (0 of 4). This simple and early prognostic index, derived from the assessment of clinical conditions which were easily determined at the patient's bedside, could be useful for outcome prediction in ARF patients requiring renal replacement therapy.

Effects of dopamine, dopexamine and dobutamine on renal excretory function during experimental sepsis in conscious rats

BACKGROUND

Acute renal failure is a frequent complication in human sepsis. Various inotropic drugs are often used to improve central haemodynamics and renal function. The differential preservative role of the most commonly used inotropic drugs on renal function, in this condition, has previously not been extensively studied. The aim of this experimental animal study was therefore to compare the preserving effects of dopamine, dopexamine, dobutamine and saline on renal excretory function, after induction of sepsis in conscious rats.

METHOD

The effects of dopamine (DA) (2.5 micrograms.kg-1.min-1; n = 11), dopexamine (DX) (1 microgram.kg-1.min-1; n = 10), dobutamine (DB) (5 micrograms.kg-1.min-1; n = 10) and saline (n = 13) on the glomerular filtration rate (GFR), urine flow (UF), sodium excretion (SE) and fractional urinary excretion of sodium (FUENa) were studied and compared in conscious rats subjected to a 1-h infusion of live E. coli bacteria (10(9)/h).

RESULTS

In the saline-treated control group, bacteria infusion decreased GFR, UF, SE and FUENa by 31%, 53%, 51% and 36% respectively, associated with a 16% decrease in mean arterial pressure (MAP), and a 10% increase in heart rate (HR). In the post-E. coli treatment period, the fall in MAP was less pronounced with DX compared to both DB and control, while there was no difference between DX and DA. The increase in HR was most pronounced with DB. GFR decreased to a lesser extent with DX compared to DA, DB and control. UF and SE were better maintained with DX compared to DB and control, while there was no difference in FUENa between the groups.

CONCLUSION

We conclude that dopexamine, to a greater extent than dopamine and dobutamine, improves renal excretory function in experimental septic shock.

Comparison of predicted with measured creatinine clearance in cardiac surgical patients

OBJECTIVE

To determine whether creatinine clearance can be determined from a single plasma creatinine measurement in patients up to 5 days after cardiac surgery.

DESIGN

Observational longitudinal study.

SETTING

Cardiac intensive care unit in a tertiary referral center for cardiothoracic surgery.

PATIENTS

Seventy-five patients (54 men, 21 women) scheduled for elective coronary artery surgery (93 postoperative patient days).

INTERVENTIONS

Creatinine clearance measurement using a 4-hour urine collection and a single arterial blood sample.

MEASUREMENTS AND MAIN RESULTS

There was significant agreement (Deming analysis r = 0.63-0.84, correlation r = 0.76-0.95, p < 0.05) between the predicted creatinine clearance and the measured creatinine clearance on each of the postoperative days. This was maintained even if the patients required inotrope or vasoconstrictor therapy, were receiving parenteral nutrition, or had changing renal function (Deming analysis r = 0.67-0.7; correlation r = 0.8-0.93, p < 0.001) but does not apply to patients with preexisting renal dysfunction (Deming analysis r = 0.36; correlation r = 0.57, p = 0.002).

CONCLUSIONS

In cardiac surgical patients with normal preoperative renal function, predicted creatinine clearance is as reliable as measured creatinine clearance up to the fifth postoperative day.

Management of acute renal failure: new perspectives

Despite major developments in medicine, surgery, and intensive care, acute renal failure (ARF) still remains a common problem affecting approximately 5% of all general hospital patients. Mortality of all forms of ARF continues to be greater than 50%, and this percentage has not decreased significantly over the last 30 years. There are multiple factors, which may explain the persistence of such high mortality; the most important of these is probably the evolution of the disease spectrum underlying the development of ARF. At present, ARF is more often observed in older or more complex patients frequently in association with multiorgan system failure. The annual cost of managing ARF is staggering. This article reviews several of the new strategies and approaches that have been developed to aid in the management and prevention of ARF. For example, the use of biocompatible membranes has been proven to positively influence the course of ARF, which necessitates renal replacement therapy. Although continuous renal replacement therapy has a theoretical advantage compared with intermittent hemodialysis in critically ill and hemodynamically unstable patients, there are no well-controlled clinical studies to support a beneficial effect on mortality. There is, however, good evidence that calcium channel blockers play a positive role in the management of ARF, especially that associated with cadaveric kidney transplantation. Vasoactive agents, such as dopamine, may have the advantage of increasing the urine output in patients with oliguric ARF; however, their efficacy in otherwise altering the course of ARF is not well substantiated. Finally, growth factors and atrial natriuretic peptide appear to have the potential for accelerating renal recovery and decreasing morbidity and mortality from this commonly encountered medical problem. Prospective randomized clinical studies are the key to many of the dilemmas encountered with ARF.

Respiratory failure in ANCA-associated vasculitis

OBJECTIVE

To assess the prevalence, clinical manifestations, and course of respiratory failure in all patients who tested positive for antineutrophil cytoplasmic autoantibodies (ANCA) in our clinics in the period between January 1985 and January 1993.

DESIGN

Case-series analysis.

SETTING

Three teaching hospitals in the Netherlands.

PATIENTS

Two hundred twenty consecutive patients suspected of having vasculitis and/or glomerulonephritis who tested positive for ANCA by indirect immunofluorescence and enzyme-linked immunosorbent assay.

RESULTS

Sixty-two patients had pulmonary involvement. Acute respiratory failure developed in nine. Respiratory failure was related to infections in two of them and to ANCA-associated vasculitis in seven. These seven patients uniformly presented with pulmonary hemorrhage and diffuse pulmonary infiltrates. The diagnosis of systemic vasculitis was supported by the presence of a pulmonary-renal syndrome in all patients, and by detection of antibodies to the proteinase 3 or myeloperoxidase antigen in all but one patient. Antiglomerular basement membrane antibodies were absent. The mortality was high due to hypoxic respiratory failure, pulmonary superinfections, and concomitant renal failure.

CONCLUSIONS

Acute respiratory failure due to vasculitis developed in one of every nine patients with ANCA-associated pulmonary disease. Patients usually present with pulmonary infiltrates and hemoptysis. A diagnosis of vasculitis may be further supported by analysis of the urinary sediment and determination of the ANCA target antigen. It remains to be proved that early detection of ANCA favorably affects the outcome.

Biocompatible membranes in acute renal failure: prospective case-controlled study

The mortality of critically ill patients with acute renal failure has been halved through intervention by haemodialysis. However, several reports suggest that the course of the disorder may be prolonged by this procedure. Our prospective randomised study was done to see whether the generation of inflammatory mediators by bio-compatible membranes has an adverse effect on the outcome of acute renal failure. 52 patients, similar in age, severity of acute renal failure, general disease status (APACHE II), and management of acute renal failure or its related conditions, were divided into two groups. Haemodialysis was done with cuprophane or polyacrylonitrile membranes. Cuprophane membranes induced intense activation of the complement system (as judged by measurement of C3a) and lipooxygenase pathway (leukotriene B4) resulting in alterations of neutrophil kinetics and function. The cuprophane group had a lower survival rate (38 vs 65%), a higher proportion of patients dying from sepsis (71 vs 40%), required more haemodialysis sessions (12 vs 9), and demonstrated delayed resolution and recovery from acute renal failure than the polyacrylonitrile group. The difference in mortality regarding lethal sepsis as cause of death was statistically significant. Our observations indicate that the outcome of critically ill patients with acute renal failure may be influenced by bio-incompatibility reactions to the dialysis membrane. These results have direct implications for such patients on haemodialysis.

Renal impairment after thoracotomy: incidence, risk factors, and significance

One hundred thirty patients undergoing major thoracotomy between June 1991 and June 1992 at The Royal Brompton Hospital, London, were analyzed; renal impairment developed in 31 patients (24%). The mortality and morbidity was significantly greater for the renal impairment group. Six patients (19%) with renal impairment died after operation, in contrast to 0 of the 99 patients in whom renal impairment did not develop. The average length of hospital stay for the patients with renal impairment was 12 days compared with 8 days for the normal renal function group (p << 0.001). Five factors were highly significantly associated with renal impairment: a past history of renal impairment or diuretic intake, undergoing pneumonectomy, postoperative infection, and blood loss (p < 0.001). The most important of these appears to be postoperative infection or blood loss, as they also were associated with death (p = 0.01). Other factors less significantly associated with renal impairment included a past history of hypertension, ischemic heart disease, intraoperative gentamicin, and epidural analgesia (p < 0.01). This study emphasizes that thoracotomy must be considered carefully in patients with these predisposing factors, particularly if pneumonectomy is likely. Care must be taken in the use of aminoglycosides and epidural analgesia. Maintenance of renal blood flow by careful control of hemodynamic indices appears to be the most important intervention.

Acute renal failure in a medical setting: changing patterns and prognostic factors

The clinical characteristics of 118 patients (60 male) with acute renal failure (ARF) admitted between 1980 and 1991, were retrospectively analyzed and compared with our earlier series of the 1960s. The mean age was 53 years (16-82 years). There was a marked decline in the hypotension-related cases (43% vs. 17%, p < 0.01) and a concomitant increase in the nephrotoxic cases (5% vs. 17%, p < 0.005) in recent years. The number of ARF cases significantly decreased after 1986 (31%) compared to the pre-1986 era (69%, p < 0.001). A complete (35%) or partial recovery (55%) was the rule in the majority of the patients. The overall mortality was 27%, virtually unchanged in comparison to the 1960s (30%). However, a tendency toward lower mortality was seen after 1986 (17%) in comparison to before (32%, p < 0.05). Sepsis and cardiovascular complications were the leading causes of death. Fewer deaths were observed among younger patients (< 30 years, 12.5%) compared to middle-aged patients (30-59 years, 34%, p < 0.05) and to these older than 60s (53.5%, p < 0.002). Also, deaths were rare in patients with only renal involvement (6%), increasing to 30% when 2 vital organ systems were affected (p < 0.005) and to 67% in cases with multiple organ failure (p < 0.001). Early institution of dialysis and the nonoliguric forms of the syndrome seem to be associated with better prognosis. In conclusion, the incidence of ARF has declined in recent years, with a concomitant tendency towards lower mortality. Death rate is mainly determined by the age and the number of organ involvement. Early dialysis seems to contribute to the lower mortality seen in recent cases.

Continuous veno-venous haemofiltration following cardio-pulmonary bypass. Indications and outcome in 35 patients

OBJECTIVE

To study the impact of continuous veno-venous haemofiltration on survival in patients with acute renal failure (ARF) following cardio-pulmonary bypass (CPB) surgery.

DESIGN

A retrospective study of all patients requiring haemofiltration after CPB over a 2 year period.

SETTING

A 20 bedded, adult cardothoracic intensive care unit in a postgraduate teaching hospital.

PATIENTS

35 patients (26 male, age range 24-74 years) required haemofiltration (2.7% of the total number of patients undergoing CPB).

MAIN RESULTS

Cardiovascular failure post CPB was the commonest causes of ARF (n = 16). Indications for haemofiltration were uremia (21), oligo-anuria (11), volume overload (2) and hyperkalaemia (1). Mean time from CPB to the initiation of haemofiltration was 8 days (range 0-15 days). Mean urea was 30 mmol/l and creatinine 362 mumol/l immediately prior to treatment. Urea was well-controlled in all patients, although 2 needed haemodiafiltration. Twenty-six patients died during their admission to the ICU (74% mortality). A further 3 patients died during their hospital admission, following discharge from ICU. Outcome was particularly poor in patients with cardiovascular failure following CPB (16 cases, 0 survivors). Survivors tended to commence filtration earlier (mean of 4 vs 7 days for non-survivors) and required treatment for a mean period of 8 days (range 1-26 days). Survival was determined by the number of failed organ systems at the start of haemofiltration. Thus, 100% of patients with single system failure survived, compared to only 10% with 3 or more system failure.

CONCLUSIONS

Despite the theoretical advantages of haemofiltration and the effective control of uraemia the mortality associated with ARF following CPB remains high and is probably determined by the number of failed organs systems.

Dopamine and renal salvage in the critically ill patient

Dopamine is a catecholamine used widely in critically ill patients and those undergoing major surgery, often as a 'renal protective' agent. Direct renal vasodilatation with 'low-dose' dopamine is the widely accepted basis for its use--hence the term 'renal dose' dopamine. However, recent evidence has revealed that the renal effects of this agent are far more complex. Moreover, some of these effects may be undesirable in the 'at-risk' kidney. The increased renal blood flow (RBF) of dopamine may be largely attributable to its inotropic (myocardial) action, even with low doses (i.e. less than 5 micrograms/kg/min). Similar increases in RBF can also be demonstrated with other (non-dopaminergic) inotropes. The early evidence for direct renal vasodilatation in response to dopamine has been brought into question by more recent research. The diuresis and natriuresis commonly seen following dopamine administration is now known to be due to a direct renal tubular (or 'diuretic') action. Furthermore, increasing knowledge regarding the pathophysiology of acute (ischaemic) renal failure, including RBF and the concept of 'oxygen supply and demand' in relation to tubular function, suggests that dopamine may mask important signs of renal ischaemia. Whether or not dopamine is truly beneficial to renal function currently remains unanswered. As it stands however, there is sufficient evidence to question its routine use in the setting of renal dysfunction in the critically ill patient.

Ischemic acute renal failure

Underperfusion of the kidneys often results in the development of ischemic acute renal failure. This review summarizes the recent developments in the understanding of the pathophysiology, diagnosis, and treatment of this serious and costly disorder that affects almost 5% of hospitalized patients.

Renal function not impaired by hip arthroplasty. A prospective study of 26 patients

To evaluate the importance of various changes during major surgery, 26 patients, electively chosen for total hip replacement (THR), were investigated for renal function preoperatively and postoperatively. In most of the patients, surgery was performed ad modum Charnley (n 25), and anesthesia was given mainly by continuous administration of bupivacaine or mepivacaine through an epidural catheter. Postoperatively, there was an improvement in glomerular filtration rate (GFR) and a reduction in renal concentrating ability (RCA), but no change in diurnal albumin excretion. No correlation was found between the change in GFR and, e.g., the degree of peroperative hypotension, bleeding, transfusions, or volume of infusions. There was a correlation between the impairment of RCA and the lowering of serum albumin concentration. In 3 patients the GFR was slightly impaired. The risk of contracting severe, acute renal failure seems low in THR performed on patients with reduced or normal kidney function.

Five years experience with continuous extracorporeal renal support in paediatric intensive care

Continuous arterio-venous haemofiltration (CAVH) and continuous veno-venous haemofiltration (CVVH) were used as renal support in 52 critically ill infants and children with acute renal failure. The majority of the patients were on mechanical ventilation (90%) and needed vasopressor support (85%). Uraemia was satisfactorily controlled with both treatment modes. Post-treatment serum urea levels were not different between survivors (94 +/- 8.8 mg/dl) and non-survivors (99.5 +/- 8.8 mg/dl). There were significant differences between survivors and non-survivors in the mean arterial pressure (64.7 +/- 3.8 vs 48.0 +/- 2.2 mmHg, p less than 0.001), the number of organ system failures (2.9 +/- 0.16 vs 3.8 +/- 0.21, p less than 0.025), and the severity of illness assessed by the acute physiologic score for children (APSC 19.4 +/- 1.9 vs 26.3 +/- 1.9, p less than 0.01). The overall mortality was 48%. The mortality in the CVVH group (65%) was higher than in the CAVH group (40%). Death was significantly related to sepsis (p less than 0.005) and multiple system organ failure (p less than 0.005). A major complication during CAVH was one femoral artery thrombosis after 12 days of treatment. Technical problems were only observed during CVVH. CAVH and CVVH are safe and effective methods of continuous renal support for critically ill paediatric patients with multiple system organ failure. CAVH is simpler, needs no specially trained staff and seems to the ideal renal replacement system for critically ill infants.

The consequences of continuous haemofiltration on lung mechanics and extravascular lung water in a porcine endotoxic shock model

Endotoxinaemia (E. coli endotoxin, 0.111.B4) and pulmonary hypertension were evoked in 20 swine, randomly assigned to receive either zero-balanced venovenous haemofiltration (HF) with an ultrafiltration and replacement rate of 600 ml/h (HF group, n = 10) or to undergo an uninfluenced spontaneous course (E group, n = 10) during a constant infusion of endotoxin until the end of the experiment. Endotoxin-induced pulmonary dysfunction was assessed on the basis of extravascular lung water (EVLW) using a thermo-dye technique via a fiberoptic intra-aortic probe, gas exchange and lung mechanics, the latter derived by a pressure-volume loop (P/V loop) of the respiratory system (super syringe, flow 30 ml/s, tidal volume 600 ml). A comparable increase in alveolo-arterial oxygen difference and a constant EVLW was observed in both groups. The progressive deterioration of hysteresis area and compliance parameters by endotoxinaemia was significantly blunted by HF. Independent of an impact on pulmonary oedema zero-balanced HF modifies endotoxin induced lung injury, probably by the convective transport of mediator substances.

The cost of an intensive care unit: a prospective study

The cost of intensive care for patients admitted to the ICU were estimated. Patients suffering from severe combined acute respiratory and renal failure who required mechanical ventilation and renal replacement therapy (SCARRF-D) cost per day significantly more than non-renal patients (pounds 938 compared to pounds 653 per patient respectively) and their average length of stay in hospital is nearly 4 times as long (28.8 compared to 7.6 days respectively). Approximately 44% of the total cost was staff related (28% for the provision of nurses and 16% for the rest). Retrieving information related to cost was difficult, time consuming and labour intensive.

The optimization of renal function in acute illness

The development of acute renal failure increases the morbidity, the mortality and the duration of hospital stay of all patients who are treated in intensive-care units. Consequently, the prevention of renal failure, and especially that of oliguric acute renal failure, has a high priority in the management of patients who are seriously-ill. The identification of risk factors, the pretreatment of patients who are in high-risk categories and the maintenance of adequate hydration, oxygenation, cardiac output and renal blood flow are the first-line priorities in management. The use of loop diuretic agents, mannitol and dopamine, separately or in combination, probably are effective prophylactic measures. They also may have therapeutic benefit in the maintenance of a non-oliguric state in the presence of acute renal failure, although there is less scientific support for this role. Such manoeuvres are worthy of trial before an oliguric state is accepted. They are more likely to be efficacious if they are instituted early.

A key to the literature of total parenteral nutrition: update 1987

This comprehensive bibliography is intended to enhance the education of the practitioner, student, and academician in the area of parenteral nutrition. This bibliography is not all-inclusive but serves as an update from the original published in 1983. Of particular note in this work is the addition of topics that reflect a growing interest in medical specialties with regard to patient nutritional status and support.

Renal and liver function tests in surgical septicemia

The prognostic value of conventional renal and liver function tests was evaluated during surgical septicemia. Changes in renal function variables were associated with the development of septic shock. Creatinine clearance was the most sensitive variable in predicting the outcome of septic shock, but serum creatinine and urine output were also of some value in this respect. Significantly lower creatinine clearance and urine output values, as well as significantly higher serum creatinine concentrations, were thus observed during septic shock with fatal outcome compared to non-fatal septic shock. In septicemia not complicated with shock, the variables of renal function remained in the normal range irrespective of final outcome. Among the liver function tests, serum albumin and total protein concentration revealed significant differences in behaviour between survivors and patients dying with persistent septicemia. However, due to the small differences and considerable overlap observed between the two groups of patients during the first 2 weeks of septicemia, these two variables are of limited practical value as prognostic predictors. The other liver function tests gave no information as regards the outcome of septicemia in the present study.